Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a pose calibration method and a pose calibration system for an in-situ mounting line laser sensor of a five-axis machine tool.
The invention provides a pose calibration method of an in-situ mounting line laser sensor of a five-axis machine tool, which comprises the following steps:
the installation step: installing a line laser sensor and a calibration block and connecting a line laser communication system;
a deviation value β compensation step, namely calculating a deviation value β according to the inclination of the laser line direction and compensating the deviation value β;
an offset α compensation step, namely, rotating the A axis, calculating an offset α and compensating the offset α;
extracting characteristic points: scanning the circular feature of the calibration block by translating the Y axis of the machine tool, and extracting the feature point of the circular edge;
and a five-axis compensation step, namely adjusting the zero position of the five axes of the machine tool X, Y, Z, A, B to compensate position deviations delta x, delta y and delta z and attitude deviations α and β.
Preferably, the mounting step comprises: the method comprises the steps of installing a linear laser sensor on a machine tool spindle, connecting a laser communication system, installing a calibration block on a machine tool workbench, and adjusting the upper plane of the calibration block to be parallel to the XOY plane of the machine tool.
Preferably, the offset β compensating step includes adjusting the B-axis zero offset β to indicate the deviation angle between the laser equidistant line perpendicular to the central laser direction and the XOY plane of the machine tool in the initial laser attitude, which is equal in value to the complementary angle between the central laser direction and the XOY plane deviation angle.
Preferably, the offset value α step includes rotating the A axis to obtain the difference
The calculation formula of the following parameter h is as follows:
fitting a deviation value α by a least square method, and compensating the deviation value α by adjusting the zero position of the A axis;
wherein h represents: the linear distance from the line laser center to the measured plane along the laser line direction, namely the laser ranging distance from the line laser center to the plane, is obtained by reading of a laser, and a dependent variable is formed in the rotation of an A axis;
l represents: the linear distance from the rotation center of the A shaft of the machine tool to the measured plane;
n represents: the linear distance from the rotation center of the A shaft of the machine tool to the laser emission origin of the laser device;
σ represents: the zero position of the A axis is the deflection angle between the laser line direction and the XOZ plane under the original installation posture state of the laser;
represents: the X-axis forward visual angle and the A-axis clockwise rotation angle;
α indicates the angle of the current laser line direction to the machine tool Z axis.
Preferably, the extracting the feature points step includes: according to the characteristic points of the circular edge, the following formula is obtained:
wherein x represents: the X component of the intersection point of the line laser and the circular groove boundary in the coordinate of the workpiece coordinate system;
y represents: the Y component of the intersection point of the line laser and the circular groove boundary in the coordinate of the workpiece coordinate system;
x0、y0represents: x, Y coordinates of the center of the circular groove in a laser coordinate system;
x ', y' represent: the coordinates of the intersection point of the line laser and the boundary of the circular groove in a laser coordinate system are obtained by calculating the position of the machine tool and the reading of the line laser;
r represents: the radius of the round groove of the block is calibrated, the size is designed according to the measurement range of the line laser, and the actual size is given by a three-coordinate measuring machine;
θ represents: the deviation angle between the connecting line of the intersection point of the line laser and the boundary of the circular groove and the circle center and the X axis;
γ represents: the included angle between the current laser line direction and the X axis of the machine tool;
from the circular equation of the calibration block we obtain:
r2=(x′-x0)2+(y′-y0)2+2(x′-x0)(y′-y0)sin(γ)
fitting the parameter x using a least squares method from the obtained feature point coordinates (x', y0,y0Gamma, the theoretical position of the center of the circular hole of the calibration block is measured by a three-coordinate measuring machine and is given as0,y0The difference of (d) is δ x, δ y.
Preferably, the five-axis compensation step comprises: and (4) adding a gamma angle through machine tool kinematic transformation, and compensating the attitude deviation gamma.
The invention provides a pose calibration system of a five-axis machine tool in-situ mounting line laser sensor, which comprises the following steps:
installing a module: installing a linear laser sensor to a machine tool spindle, connecting a laser communication system, installing a calibration block to a machine tool workbench, and adjusting the upper plane of the calibration block to be parallel to the XOY plane of the machine tool;
the deviation value β compensation module is used for calculating a deviation value β according to the inclination of the laser line direction, adjusting a B-axis zero compensation deviation value β to represent the deviation angle between a laser equidistant line vertical to the central laser direction and the XOY plane of the machine tool in the initial posture of the laser, wherein the deviation angle is equal to the complementary angle of the deviation angle between the central laser direction and the XOY plane;
the deviation value α compensation module rotates the A shaft, calculates a deviation value α and compensates the deviation value α;
a feature point extraction module: scanning the circular feature of the calibration block by translating the Y axis of the machine tool, and extracting the feature point of the circular edge;
and the five-axis compensation module is used for adjusting the zero position of the five axes of the machine tool X, Y, Z, A, B to compensate position deviations delta x, delta y and delta z and attitude deviations α and β.
Preferably, the offset value α module includes rotating the A axis to obtain the difference
The calculation formula of the following parameter h is as follows:
fitting a deviation value α by a least square method, and compensating the deviation value α by adjusting the zero position of the A axis;
wherein h represents: the linear distance from the line laser center to the measured plane along the laser line direction, namely the laser ranging distance from the line laser center to the plane, is obtained by reading of a laser, and a dependent variable is formed in the rotation of an A axis;
l represents: the linear distance from the rotation center of the A shaft of the machine tool to the measured plane;
n represents: the linear distance from the rotation center of the A shaft of the machine tool to the laser emission origin of the laser device;
σ represents: the zero position of the A axis is the deflection angle between the laser line direction and the XOZ plane under the original installation posture state of the laser;
represents: the X-axis forward visual angle and the A-axis clockwise rotation angle;
α indicates the angle of the current laser line direction to the machine tool Z axis.
Preferably, the feature point extracting module includes: according to the characteristic points of the circular edge, the following formula is obtained:
wherein x represents: the X component of the intersection point of the line laser and the circular groove boundary in the coordinate of the workpiece coordinate system;
y represents: the Y component of the intersection point of the line laser and the circular groove boundary in the coordinate of the workpiece coordinate system;
x0、y0represents: x, Y coordinates of the center of the circular groove in a laser coordinate system;
x ', y' represent: the coordinates of the intersection point of the line laser and the boundary of the circular groove in a laser coordinate system are obtained by calculating the position of the machine tool and the reading of the line laser;
r represents: the radius of the round groove of the block is calibrated, the size is designed according to the measurement range of the line laser, and the actual size is given by a three-coordinate measuring machine;
θ represents: the deviation angle between the connecting line of the intersection point of the line laser and the boundary of the circular groove and the circle center and the X axis;
γ represents: the included angle between the current laser line direction and the X axis of the machine tool;
from the circular equation of the calibration block we obtain:
r2=(x′-x0)2+(y′-y0)2+2(x′-x0)(y′-y0)sin(γ)
fitting the parameter x using a least squares method from the obtained feature point coordinates (x', y0,y0Gamma, the theoretical position of the center of the circular hole of the calibration block is measured by a three-coordinate measuring machine and is given as0,y0The difference of (d) is δ x, δ y.
Preferably, the five-axis compensation module comprises: and (4) adding a gamma angle through machine tool kinematic transformation, and compensating the attitude deviation gamma.
Compared with the prior art, the invention has the following beneficial effects:
1. by adopting a mode of scanning the calibration block, the problem that the mounting initial position and attitude deviation of a laser main shaft in the in-situ mounting line laser measurement method are difficult to calibrate, thereby influencing the in-situ measurement precision of line laser is solved;
2. by the analysis method of least square fitting of the scanning result, the problem that the influence of accidental errors in single measurement on the analysis result is too large is solved;
3. the method for adjusting the zero position of each shaft of the machine tool and compensating the kinematic transmission chain of the machine tool in the laser measurement result solves the problem that the initial installation deviation of the linear laser in-situ measurement main shaft is difficult to compensate.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
The invention provides a pose calibration method of a five-axis machine tool in-situ mounting line laser sensor, which comprises the following steps:
step one, mounting a linear laser sensor to a machine tool spindle, connecting a linear laser control communication system, mounting a calibration block to a machine tool workbench, leveling and ensuring that the upper plane of the calibration block is parallel to the XOY plane of the machine tool;
step two, as shown in fig. 4, calculating a deviation value β by the inclination of the laser line direction, that is, the deviation angle between the measurement result straight line and the horizontal line when the laser line is on the measurement theory XOY plane;
step three, as shown in fig. 5, the parameter h values under different phi can be obtained by rotating the axis a, and the parameter in the graph can satisfy the equation through the geometric relationship:
fitting a deviation value α by a least square method;
step four, as shown in fig. 6, the Y axis of the translation machine scans the circular feature of the calibration block, and extracts the feature point of the circular edge, and due to the existence of the offset, the feature point is similar to an ellipse, and the following equation can be obtained by the geometric relationship:
the theoretical circular equation based on the calibration plate can be obtained as follows:
r2=(x′-x0)2+(y′-y0)2+2(x′-x0)(y′-y0)sin(γ)
according to the obtained series of characteristic point coordinates (x ', y'), fitting parameters x0, y0 and gamma by using a least square method, wherein the theoretical position of the center of the circular hole of the calibration plate is measured by a three-coordinate measuring machine, and the difference between the theoretical position and the theoretical positions of the center of the circular hole of the calibration plate are delta x and delta y; as shown in fig. 3, a sensor installation pose deviation parameter definition map is shown;
and step five, compensating the position deviations x, y and z and the attitude deviations α and β by adjusting the zero position of five shafts of the machine tool X, Y, Z, A, B, and compensating the attitude deviation gamma by adding a gamma angle in the kinematic transformation of the machine tool.
Line laser normal position installation position appearance calibration system includes: the system comprises a five-axis machine tool, a linear laser sensor (named as a 2D laser profile instrument), a calibration block mounting device and a linear laser control communication system.
The five-axis machine tool 1 is in an X-Y-Z-A-B transmission form and providesA support platform for in-situ measurement; the line laser sensor comprises a commercially available 2D laser profile instrument 201 and support parts 202 for installing a laser to a spindle of a five-axis machine tool in a matching manner, wherein the design and processing of the support parts 202 need to ensure an installation interface with the laser profile instrument 201 and an installation interface with the spindle of the 1; as shown in fig. 2, which is a calibration block part diagram, the calibration block 3 is a machined part, the whole shape of which is a rectangular aluminum block, and one surface of which is milled to generate a graphic characteristic; the calibration block mounting device 4 is a standard clamping tool for stably mounting the calibration block 3; the line laser control communication system 5 comprises a numerical control system 501, a line laser controller 502 and a switch 503, wherein the line laser controller 502 is connected with the line laser sensor 201 through a cable and collects measurement data of the line laser sensor 201, the line laser controller 502 is connected with the line laser sensor 501 through an Ethernet line, the line laser controller 502 communicates with the line laser sensor 501 through an Ethernet protocol, the measurement data of the line laser sensor 201 are forwarded to the line laser controller 501, the line laser controller 501 records the laser data sent by the line laser sensor 502 and synchronously integrates the laser data with position information of the line laser controller 1 recorded by the line laser controller, and a recording file in which the machine. The file results recorded by the system are analyzed by designing the characteristics of the calibration block and a laser scanning mode, the values of variables representing the relative positions and postures of the in-situ installation of the line laser sensor on the five-axis machine tool shown in fig. 1 are finally obtained, and the offset quantities are compensated through the zero point setting and the kinematic transformation of the machine tool.
In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.
Those skilled in the art will appreciate that, in addition to implementing the systems, apparatus, and various modules thereof provided by the present invention in purely computer readable program code, the same procedures can be implemented entirely by logically programming method steps such that the systems, apparatus, and various modules thereof are provided in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system, the device and the modules thereof provided by the present invention can be considered as a hardware component, and the modules included in the system, the device and the modules thereof for implementing various programs can also be considered as structures in the hardware component; modules for performing various functions may also be considered to be both software programs for performing the methods and structures within hardware components.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.